Fuel injection systems for motor vehicles operate to provide accurate amounts of fuel to each cylinder in order to achieve a predetermined fuel/air ratio for purposes of combustion and operability of the engine. Most fuel injection systems are a combination of electronics and electromechanical devices. The responsibility of the electronics is to calculate the amount of fuel to be delivered to the cylinder and one of the electromechanical devices, the fuel injector, operates to deliver the calculated amount of fuel to the cylinder.
Most fuel injectors are actuated by a precise time length electrical pulse and during the actuation time, fuel is supplied from the injector. Both the opening time and the closing time of the injectors are controlled. Many factors influence the amount of fuel supplied by the injector. Some of these factors are the fuel pressure, the "lift" of the injector needle, the speed in which the injector valve opens and the speed in which the injector valve closes, the length of the actuation pulse, the size of the orifice or orifices through which the fuel flows, etc.
Depending on the type and style of fuel injector, there is a plate member between the valve seat and the end of the injector which directs the flow of fuel. Contained on this plate member is one or more orifices of precision size. Once the valve is opened for the predetermined period of time, the orifice or orifices control the amount of fuel actually discharged from the injector. Because of manufacturing techniques, the "cleanness" and the size of the orifices require each injector to be adjusted for the proper flow rates. This is a labor intensive task and therefore increases the cost of the injector.
Previous methods of manufacturing orifice disks have used Electrical Discharge Machines (EDM) for cutting the orifice by means of a controlled electrical discharge. Other methods have used laser beams, photo-etching, or basic drill and ream techniques to form the orifice. All of these, while they have been successful to some degree, have not been without high unit cost.
Modern fuel injectors have no adjustments to be made after the injector is assembled and therefore the size of the orifice or orifices must be held to very close tolerances. This is typical of all orifices in every fuel injector and problems in flow rates are still present. To further solve the problem of maintaining desired flow rates, with all other factors in the fuel injector design remaining unaffected, the manufacturing apparatus and process for manufacturing an orifice disk for fuel injectors was developed.